Device for feeding sheets



Oct. 13, 1970 J. v. CARSTENS 3,533,618

DEVICE FOR FEEDING SHEETS Filed June 5, 1968 2 Sheets-Sheet 1 FIGS FIG] INVENTOR Tdr'gen Cawsiens ATTORNEYS Oct. 13, 1970 J. v. CARSTENS 3,533,518

DEVICE FOR FEEDING SHEETS Filed June 5, 1968 2 Sheets-Sheet 2 FIG.5

INVENTOR ATTORNEW United States atent O f U.S. Cl. 271-51 6 Claims ABSTRACT OF THE DISCLOSURE The invention relates to a device for feeding sheets, e. g. paper sheets, which are drawn against the surface of the suction roller by means of a vacuum. In the surface of the suction roller are grooves, the lengths of which may be greater than the width of the sheet and in the grooves are apertures for being connected to a vacuum source. When the suction roller rotates, the inlet of said apertures passes a short distance from an independently pivotable suction shoe having an aperture, the inlet of which is connected to the vacuum source. The suction shoe is movable towards the suction roller, but is kept at a short distance from the suction roller by a suitable force, which can be overcome by the vacuum when a sheet is placed on the roller, so as to cover the grooves in register with the aperture in the suction shoe.

When a sheet covers said grooves, the suction shoe is, by the vacuum thereby becoming effective, drawn against the rotating roller and by contact with the rotating roller carried along with this roller until a stop for the suction shoe is reached.

Until the stop is reached, the sheet is gripped continuously by the vacuum at the leading edge. When the stop is reached and the roller continues the rotation, the zone in which the sheet is gripped, moves backwards from the leading to the lagging end of the sheet. At last the lagging end of the sheet leaves the gripping zone moved by the rotating roller, thereby permitting a larger quantity of air to reach the apertures in the grooves, so that the force on the suction shoe is no longer overcome and the suction shoe is consequently retracted. When losing contact with the suction roller, a resetting force carries the suction shoe to the initial position, ready for renewed action.

Two conditions are necessary for the feeding of a sheet by the suction roller, namely the presence of a vacuum and the presence of a sheet at the groove or grooves in register with the suction shoe. This fact opens up different possibilities for controlling the start of the feeding. The device can be utilized, inter alia, for feeding sheets or opening and feeding folded sheets.

The invention relates to a device for feeding sheets by means of a rotary feeding member, a suction roller, against which the sheet is drawn by a vacuum.

Devices of this type are employed in machines used in bookbinding works, e.g. in the form of a rotary, hollow cylindrical feeding member, in which a stationary suction shoe is provided, which supplies a vacuum to a part of the inner side of the cylinder provided with openings, so that on the outer side of the cylinder there is produced a suction over an area determined by the size of the suction opening in the suction shoe and by the design of the openings in the cylinder. The suction area is, during the rota- 'ice tion of the cylinder, displaced along the surface of the cylinder. Viewed in relation to the sheet advanced, the suction area moves constantly to the rear from the front edge of the sheet during the feeding of the sheet.

It is an object of the present invention to provide a device in which during the feeding of the sheet the suction area can remain in the zone at or near the front edge of the sheet during part of the feeding movement. Such a construction offers a series of advantages and increases the possibilities of application. The mechanism can, for example, be utilized for the opening of folded sheets.

The device according to the invention is characterized by a vacuum supply member, a suction shoe which cooperates with the suction roller, but is pivotable independently of the latter and arranged for being carried along by the suction roller, so that the suction area follows the suction roller over a predetermined distance.

The invention will in the following be further explained with reference to accompanying diagrammatical drawings, in which FIGS. 1 to 4 show an embodiment of a device according to the invention in four different stages during the feeding of a sheet, the direction of movement of which is deflected by 7 FIG. 5 shows an embodiment of part of a suction roller for a device according to the invention with an internal suction shoe and viewed in partial section, and

FIGS. 6 and 7 viewed in the axial direction and in section, respectively show part of an embodiment of a device according to the invention comprising an external suction shoe.

In the diagrammatical FIG. 1, numeral 1 designates a feeding member, which is designed as a suction roller and shown in section revealing the suction openings disposed along the circumference in a radial plane. One of the said openings is denoted by 2. Such suction openings are in a suitable way distributed along generatrices on the suction roller. The suction roller must be imagined to move at a constant velocity in the direction of the arrow A in FIG. 1. The rotary movement may, for example, be provided in the way indicated in FIG. 6 by means of a belt drive or a chain drive. The shaft 3 of the suction roller is hollow and serves for supplying a vacuum to a suction shoe 4 extending a distance in the axial direction, which may correspond to the length of the suction area desired. The suction shoe 4 having an elongated axial slot is mounted pivotable on the shaft 3 with the axial slot allowing movement in the radial direction, as will appear from a comparison between FIG. 1 and FIG. 2. In the latter figure, the suction shoe contacts the inside of the suction roller 1. The suction shoe 4 is actuated by a setting device, not shown, e.g. a torsion spring or a vacuum mechanism. After the feeding of a sheet is finished, the setting device resets the suction shoe into the position shown in FIG. 1, the said position being determined by a stop member 5. Another stop member 6 limits the angle through which the suction shoe 4 is turned counterclockwise during operation. The two stop members 5 and 6 may be adjustable.

The suction shoe 4 comprises an axially extending suction duct, which is shown dotted at 7 and which is in communication with a vacuum supply line, not shown, which is connnected to the hollow shaft 3.

P designates a sheet, e.g. a paper sheet, which in some way or other is fed to the rotary roller. At the moment when the front edge of the sheet arrives at the suction roller and closes a row of holes along a generatrix on the suction roller 1, the suction shoe 4 will move radially, being drawn against the inner side of the suction roller 1. Due to the friction between the suction shoe 4 and the suction roller 1, the suction shoe 4 will be carried along with the suction roller 1 in the direction opposite to that of the setting device, not shown. This causes the front edge of the sheet to remain under a vacuum and thus to be drawn continuously against the suction roller, while the suction area in the space moves along a circular arc until the suction shoe 4 is stopped by the stop member 6. When this has happened, the suction roller and thereby the sheet continue their movement, while the suction shoe 4 remains stationary, with the result that the suction area now remains stationary in space, but in relation to the sheet is displaced in the direction from the front edge of the sheet to its rear edge. FIG. 3 shows the moment when the movement of the suction shoe is stopped, while FIG. 4 shows the position shortly afterwards.

From FIGS. 1 and 4 it appears that during the feeding the sheet has had its direction of movement deflected by 90. The size of the angle may be adjusted by an adjustment of the stop members 5 and 6.

The device shown in FIGS. 1 to 4 can be used for opening folded sheets advanced with the folded edge lagging. The rigidity of the material will entail that the upper part of the folded sheet will continue along the tangent, indicated by dotted line 8 in FIG. 3, while the lower part of the sheet will be curved around the suction roller.

If desired, two suction rollers may be used, the outer surfaces of which almost touch, so that each of the two parts of the folded sheet is gripped by its suction roller. Should it be desired to have the opened sheet riding on an ordinary conveyor, the axes of the two suction rollers may be disposed on a horizontal plane, while the paper sheet is supplied vertically between the two rollers. The device according to the invention offers the advantage that the conveyor can be placed quite closely to the suction rollers, so that the distance the sheet has to drop in its opened state is shortened, which diminishes the risk of wrong delivery. The opening angle can be made optionally large, e.g. even 180".

The return of the suction shoe 4 from the position shown in FIG. 4 is effected by means of the resetting device, not shown, as soon as the rear edge of the paper sheet P has left the suction area, the friction between the suction shoe 4 and the suction roller 1 being reduced when air makes its way in through the suction openings in the suction roller 1.

The device according to the invention is distinguished by being uncritical with regard to dimensions. This applies e.g. to the distance between the suction shoe 4 and the inside of the suction roller 1, which means that a reliable functioning is preserved after even prolonged use with the wear deriving therefrom.

The device may also be used for removing single sheets from a pile. It has turned out that the device works more reliably than ordinary mechanisms, and this is first and foremost due to the suction area remaining at the front edge of the paper sheet during the first part of the feeding movement.

The constructive embodiment of a suction roller shown in FIG. 5 is shown cut off at the end pointing left in the figure. In practice, the suction roller is twice as long as shown, a part symmetrical with the one shown being provided which comprises a separate suction shoe, so that as a whole the mechanism may be used either for advancing two sheets independently of each other, or for advancing single wide sheets.

The suction roller 51 has in the embodiment shown a diameter of about 70 mm. and the surface is provided with a number of sharp-edged grooves 52, in which suction openings 53 terminate. The depth of the grooves 52 is in this embodiment about 1 mm, being so dimensioned that by being drawn against the surface of the suction roller, the sheet reduces the vacuum area between sheet and roller without blocking the suction openings 53. By this measure being taken and by a suitable placing of the suction openings 53, it becomes possible to advance sheets of ditferent widths with one and the same suction roller without any special covering being performed.

In the case of abnormal sheet sizes and paper qualities it is, however, easy by means of a covering, for example in the form of a piece of adhesive tape put around the suction roller, in a simple, quick and cheap Way to attain an adaptation to the conditions. One lateral edge of each sheet is, moreover, when being supplied, guided in such a way that the sheets are advanced within the area where the suction openings are located.

With a view to feeding sheets of qualities, which are clifficult to separate, e.g. due to a high air penetrability, or due to the presence of static electricity, there may besides axial grooves be provided transverse sharp-edged grooves in the surface of the suction roller, or it may in some other way have an uneven surface.

The suction shoe, designated by 54, comprises a vacuum aperture 55, which is disposed in line with an opening 56, which, through the hollow shaft, designated by 57, is in communication with a vacuum source, not shown. The suction shoe 54, which, when not influenced by external forces, is so adjusted as not to touch the suction roller, can move radially against the elfect of springs, not shown, which springs may be adjustable. In the figure, the suction shoe is shown resting against the inner side of the suction roller 51 and therefore at a distance shown by the clearance 58 from the outside of the hollow shaft 57. In practice, the suction shoe 54 does not take up the position shown, until the suction openings 53-, in line with the suction shoe, are covered by a sheet and vacuum has been applied. Both of these conditions should be fultilled in order that a feeding of sheets may take place. This fact can be utilized for providing two different types of sheet feeding.

In the case of one type of sheet feeding, the suction roller is constantly under a vacuum, which causes the functioning of the suction roller to be dependent solely on the arrival of sheets. As soon as a sheet covers the suction openings, the feeding starts, the roller rotating constantly.

'In the case of the other type of sheet feeding, the supply of vacuum to the suction roller is controlled by a valve inserted at a suitable point of the vacuum supply line. This valve, which is not shown, is controlled e.g. electrically, mechanically or pneumatically in dependence on some function or other in the machine with which the suction roller cooperates, or only by a time pulse generator. This means that it is not the arrival of a. sheet that determines the time for starting the sheet feeding, but on the contrary, it is the starting pulse, which actuates the vacuum valve for opening.

Correspondingly, the advance of the sheet can be brought to a stop and the resetting of the suction shoe can be effected in two ways. viz. either by the sheet leaving the suction openings within the range of the suction shoe, or by the supply of a vacuum being interrupted, e.g. by the said valve being actuated.

The setting of the suction shoe is effected by means of a spiral spring 59. A handle 60 with an adjustment scale, not shown, is through a tubular member 61 connected to a stop member 62, which in this way can be adjusted with a view to adjusting the angle at which the suction shoe can be turned by the suction roller, a cam on the suction shoe abutting against the stop member. correspondingly, another adjustable stop member, not shown, can limit the movement of the suction shoe in the opposite direction.

The suction roller 51, journalled on ball bearings, of which only two, 63 and 64 are shown to the right in the figure, is turned by means of gear wheels 65 and 66, of which 66 is shown only partially.

In the embodiments of a device according to the invention shown in FIGS. l-S, the suction shoe moves radially during the suction process, but this movement can, without any deviation from the principle of the invention, be axial as appears from the embodiment example shown in FIGS. 6 and 7, where the suction roller 1 is mounted pivotable around a stationary shaft 3 and comprises suction openings 2 arranged in rows, each of which is in communication with one duct 9 terminating in openings 10 in one of the end faces of the suction roller, while the ducts 9 are closed at the other end face. A suction shoe is placed pivotable and axially displaceable on the shaft 3, which is hollow and comprises an opening 13 for the supply of a vacuum to a suction duct 12 in the suction shoe 14. Around the shaft 3, a helical spring 15 is disposed, one end of which is secured to the shaft 3 and the other end of which is secured to the suction shoe 14. The spring functions as a resetting spring for the suction shoe 14, the movement of which around the shaft 3 may be limited by stop members as indicated in FIG. 1, or as shown in FIG. 5.

During the operation, the suction roller 1 rotates, e.g. driven by means of a driving belt 16 and a motor 17. As long as no sheets are supplied to the suction roller, the suction shoe 14 takes up the position shown in the figure. As soon as a sheet with its front edge covers a row of holes 2 along a generatrix on the suction roller 1, the suction shoe 14 is drawn against the end face of the suction roller 1 and moves with the latter due to the friction. The suction area remains at the front edge of the sheet as long as the suction shoe 14 is carried along by the suction roller 1. When the suction shoe 14 abuts on a stop member, the suction roller 1 continues its movement and the two parts slide against each other. The suction duct 12, which expediently extends over at least two adjacent openings 10, is thereby gradually put in communication with different ducts 9, so that the suction area moves along the surface of the suction roller 1, until the rear edge of the sheet passes out of the suction area, whereby air makes its way into the suction duct 9, so that the pressure and thereby the friction between the suction roller 1 and the suction shoe 14 is reduced and the resetting spring can lead the suction shoe 14 back into its initial position, where it is ready for receiving a new sheet.

It is desirable that suction occurs over the full width of the sheet and in the design of the device due regard should be paid to this requirement. If, in the construction in FIGS. 6 and 7 a suction roller is provided, which is sufficiently long for handling the widest sizes of sheets, it must be taken into consideration that the use of sizes narrower than the widest size leads to part of the suc tion openings in a row not being covered by the sheet and will thus cause the entry of false air. This difliculty may be overcome by the part of the cylinder not in use being covered with a pliable piece of sheet material being wrapped around it. There may, however, also in the construction as described in connection with FIG. 5, be paid due regard to this fact, so that no special measures need be taken. A certain regulation may incidentally, be effected by an adjustment of the vacuum used and the quantity of air.

An adjustment of the length of the suction area in the axial direction of the suction roller may be effected in many different ways. Interchangeable rollers or interchangeable suction shoes may be used. The number of suction shoes may be altered, so that more are in use when wider paper sheets are used. The suction roller may also be constituted by two cylinders, one within the other, and both provided with suction openings, the outer cylinder being in the axial direction divided into sections which can be turned separately in relation to the inner cylinder, so that the suction openings can be made to lie flush with each other or lie displaced in relation to each other, in which latter case the suction area is limited. Between the inner cylinder and each of the sections of the outer cylinder a locking mechanism may be provided, e.g. a ball lock, which serves in part to retain the sections in the extreme positions in which they are set, partly for guiding their relative movements by grooves being provided in the inner surface of the sections.

In all the embodiment examples described in connection with the drawing, it is the friction between the suction shoe and the feeding member, which carries along the suction shoe. It is, however, also possible to let the advance of the suction shoe occur mechanically and possibly rhythmically, as hereby the advantage of having the sheet gripped along its front edge and advanced under constant gripping of the front edge is still preserved. In the case of a rhythmical advance, it is necessary that the sheets arrive in a regular rhythm corresponding to the rhythmical movement of the suction shoe. Even if the suction shoe is moved mechanically, the movement of the sheets need not be rhythmical, it being possible to utilize the increase in the vacuum, which occurs when a sheet closes a row of suction holes, for operating a mechanical coupling which engages the suction shoe, so that it follows the movement of the feeding member. At the termination of its movement, the suction shoe can actuate a valve, which, with a desired, preferably adjustable delay effects the return of the suction shoe to its initial position. Electric, magnetic or electromagnetic forces may also be used for providing the function desired. The pressure in the suction duct of the suction shoe may e.g. control an electric switch closing an electric circuit, the current of which excites an electromagnetic device, which couples the suction shoe to the feeding member, until the current circuit is interrupted when a part of the switch contacts a stop member. The interruption may be delayed, one of the ordinary delaying means being used.

The setting, one way or another, of the suction shoe may occur under the sole influence of the force of gravity, e.g. in the case of an at least partially vertical transport.

When the suction roller device according to the invention is used for feeding sheets taken from the bottom of a pile, there may, due to the sheet being drawn against the suction roller over the full width of the sheet, occur a registration problem, the firm grip of the suction roller on the sheet making an alignment difficult. With a view to this, there may, according to the invention in connection with the suction roller, but at right angles to the latter, be provided a rotary roller which actuates the lowest sheet in the pile into abutment against a registration abutment member on the admission side of the suction roller.

What is claimed is:

1. A sheet feeding device comprising a perforated suction roller; a tubular axle adapted to be connected to a vacuum source and having said roller rotatably mounted thereon; means for continuously rotating the roller; shoe means rotatably mounted on said axle and displaceable in the direction of the roller, said shoe means being adapted to contact the roller and follow the movement thereof; a conduit formed between the interior of said axle and bearing face of said shoe means; and means for resetting the shoe means to an initial position when no sheet closes those perforations of the suction roller which are positioned to receive vacuum from the end of said conduit in the bearing surface of the shoe.

2. A sheet feeding device as claimed in claim 1 wherein said shoe means has an elongated axial slot and is mounted to be radially displaceable on the axle and is adapted to contact the inner surface of the roller.

3. A sheet feeding device as claimed in claim 1 wherein said shoe means is mounted to be axially displaceable on the axle and adapted to contact the end surface of the roller in which end surface are formed conduits leading to the perforations in the roller.

4. A sheet feeding device as claimed in claim 1 further comprising adjustable stop means for limiting the rotational movement of said shoe means.

5. A sheet feeding device as claimed in claim 1 wherein the surface of the suction roller is provided with a plurality of sharp-edged suction grooves, each of which is adapted to prevent blocking of the perforations in the grooves by a sheet sucked against the surface of the roller.

6. A sheet feeding device as claimed in claim 1 further comprising means for controlling the connection of vacuum to the suction shoe.

8 References Cited UNITED STATES PATENTS 7/1952 Pope 27l27 US. Cl. X.R. 

